Emergency lighting is used for the path of egress illumination upon the loss of normal AC power. Some existing lighting systems use dedicated emergency lighting devices that switch or remain on when the lighting system of a building experiences a power outage. These lighting systems require emergency lighting devices in addition to the light fixtures used for normal illumination. Thus, the light fixtures used for normal illumination may not be fully utilized during a power outage.
Other lighting systems can utilize a single lighting fixture for both normal illumination and emergency illumination purposes thereby eliminating the need of a separate set of emergency lighting devices. However, the emergency operation of these light fixtures typically requires detection of normal AC power loss by a device that is powered by a separate emergency circuit, requiring additional high voltage wiring to the light fixtures.